The present disclosure relates to exhaust gas-driven turbochargers, and particularly to waste gate poppet valves for turbochargers.
In a conventional turbocharger, the turbine housing defines a bypass conduit located generally to one side of the main bore through the housing, and the bypass conduit is connected to the exhaust gas inlet or the volute of the housing via a bypass valve. The bypass or waste gate valve typically is a swing or poppet style valve comprising a circular valve member that is urged against a flat valve seat surrounding the bypass passage opening. One drawback associated with such an arrangement is that sometimes the face of the poppet valve member is not precisely parallel to the face of the valve seat, such that a gap is formed over part of the circumference through which gas can leak. Leakage past the closed bypass valve is a cause of performance degradation of the turbine and, hence, the turbocharger and its associated engine.